I know I had a bunch of .45 wolf ammo at one point and everytime I'd use it and they'd run the magnet over it, they'd make some comment that it's not good on the extractor and all that. My thought is most can change out an extractor, may cost $10-15 to do this. But over the life of say 8-10k rounds put through a gun and you are to that point you have to change it out if you've saved even $25 per 1k you're pretty far ahead. Same with .223 in AR's, may make it a little dirtier but if you don't reload and don't mind a little extra cleanup go for it. I would get a chamber brush though for a .223 and make sure to hit it hard there.
And yea the guy was an ass for not just going along with your kid, proly thought he was doing him a service by trying to make sure he didn't use any evil steel rounds. And I'm sure those ranges that do not allow the steel cases are being stingy because: 1. they don't sell steel bullets so know for sure they aren't making that money so they can atleast limit that and try to get an easy sale 2. They resell their brass and don't want to have to deal with the steel crap in the sorting process...but even if you do allow it and demand they pick it up there will always be a good amount still left on the ground anyways.
And yea the guy was an ass for not just going along with your kid, proly thought he was doing him a service by trying to make sure he didn't use any evil steel rounds. And I'm sure those ranges that do not allow the steel cases are being stingy because: 1. they don't sell steel bullets so know for sure they aren't making that money so they can atleast limit that and try to get an easy sale 2. They resell their brass and don't want to have to deal with the steel crap in the sorting process...but even if you do allow it and demand they pick it up there will always be a good amount still left on the ground anyways.